Wheel bearing device for motor vehicles

ABSTRACT

A wheel bearing device for a motor vehicle, having an inner ring arrangement, formed for rotationally fixed reception of a first rotary partner, particularly an axle stump, or a shaft, an outer ring arrangement, which is connected and/or connectable and rotationally fixed with a second rotary partner, a multitude of rolling elements, which roll between the inner ring arrangement and the outer ring arrangement, so that inner ring arrangement and outer ring arrangement and/or the rotary partners are rotatable against each other, and an electric sensor device, which, using mechanical contact, is arranged and/or formed for detecting an operating status of the wheel bearing device. The sensor device has a stationary sensor element and a rotating sensor element, which can work together to form the mechanical contact. One of the sensor elements is connected with the inner ring arrangement without the interposition of the first rotary partner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is Divisional of application Ser. No. 12/371,034 filedFeb. 13, 2009, which in turn claims the priority of DE 10 2008 009 2815filed Feb. 15, 2008, the priority of both applications is hereby claimedand both applications are incorporated by reference herein.

FIELD OF THE INVENTION

The invention concerns a wheel bearing device for a motor vehicle withan inner ring arrangement, which is formed to hold a first rotarypartner in a rotationally fixed manner, particularly an axle stump or ashaft, with an outer ring arrangement which is connected and/orconnectable with a second rotary partner in a rotationally fixed manner;with a multitude of roiling elements which roll between the inner ringarrangement and the outer ring arrangement, so that the inner ringarrangement and the outer ring arrangement and/or the rotary partnersare rotatable against each other, and with an electrical sensor device,which by the use of mechanical contact is arranged and/or designed fordetecting an operational state of the wheel bearing device, in which thesensor device contains a stationary sensor part and a rotating sensorpart, which can work together to establish the mechanical contact.

Wheel bearing devices are known in a multitude of forms and serve torotatably bear a wheel on a vehicle. The wheel bearing device usuallyhas at least one anti-friction bearing as a wheel bearing, which allowsthe turning of the wheel. These ball bearings have a life expectancyappropriate to the application purpose. During normal wear and tear, theend of its life expectancy results in increased operating noises, whichare noticed by the driver so that he can have the ball bearing replacedprofessionally in good time. Although these anti-friction bearings aremanufactured and installed to a very high standard of quality, thepossibility of them unexpectedly malfunctioning is nevertheless notcompletely ruled out. In the worst-case scenario, a sudden malfunctionof the ball bearing can even lead to losing the wheel. In this case,major consequential damage or even life-threatening situations are to befeared.

With regard to another technical field, namely for example that ofmonitoring the bearing of the propeller of a water pump, the U.S. Pat.No. 5,244,287, suggests the rotationally fixed attachment of a radiallyprojecting ring on a shaft carrying the propeller and mounted via a ballbearing, which engages with a stationary arranged bracket element,normally without contact. In the case of the ball bearing's impendingmalfunction the shaft becomes unstable so that the ring initially restsagainst the inner surfaces of the bracket element and—in the case ofincreasing instability—mechanically damages the bracket element. Thismechanical damage is detected as a break by an electric line runningthrough the bracket element. This break is evaluated and the impendingmalfunction of the ball bearing is recognised.

Another solution is described in the U.S. Pat. No. 4,063,786, whichconcerns an error detection device for a main ball bearing of agenerator in an airplane. In this error detection device, a disc is seton a rotating shaft, which, in the case of oscillations of the shaft ina radial direction, grinds a stationary positioned contact pin in anouter ring arrangement. As soon as the contact pin, as a result of thewastage, establishes electrical contact with the outer ring arrangement,a signal is activated that warns of the impending malfunctioning of themain ball bearing.

The U.S. Pat. No. 6,445,099 B1, also concerns a bearing control for agenerator, in which the shaft mounted via the ball bearing is connectedto a propeller. The bearing control is based on a ring, which is placedcoaxially to the shaft and provided with a thin conductor layer radiallyon the inside. The ring is dimensioned or arranged in such a way thatthe conductor layer is worn through in the case of incorrect radialoscillations of the shaft. As soon as the conductor layer is severed, asignal is generated which warns of a malfunction of the ball bearing.

The U.S. Pat. No. 5,865,543, that arguably presents the nearest state ofthe art, concerns a detection device for detecting the malfunctioning ofa ball bearing of a vehicle, in which the bearing is designed as a wheelbearing. In this patent, the stationary positioning of a tactile sensoron an axle stump or an auxiliary plate and monitoring as distance from abrake drum or a brake disc by means of the tactile sensor is disclosed.If the monitored distance sinks below a threshold value and/or duringcontact between the tactile sensor and the brake drum or the brake disc,a signal is activated which indicates a possible malfunction of thewheel bearing.

SUMMARY OF THE INVENTION

The invention is based on the task of proposing a wheel bearing devicewith a wheel bearing monitoring unit, which is designed ascost-effective and unsusceptible to error.

The wheel bearing device according to the invention, designedparticularly as a hub unit for a motor vehicle, is suitable for and/ordesigned for the mounting of a driven or a revolving wheel. It has aninner ring arrangement, Which is designed for the rotationally fixedsupport of a first rotary partner, above all of an axle stump or ashaft. For example the first rotary partner is pressed into the innerring arrangement or fixed in another way. The inner ring arrangement canoptionally include a first and a second inner ring, which are connectedto each other by a coupling element. Especially preferably, the innerring arrangement is formed by at least one inner ring, which externallyforms a track arranged on the inner ring and internally forms directcontact with the first rotary partner.

Alternatively to this, one or several inner ring(s) can be fitted on aninner ring carrying body of the inner ring arrangement.

An outer ring arrangement is connected and/or connectable with a secondrotary partner in a rotationally fixed manner. Preferably, the outerring arrangement has, in particular, an integrally formed outer ringbearing body, in which bearing rings are placed.

Between the inner ring arrangement and outer ring arrangement there area plurality of rolling members, preferably single-row, two or multi-row,which are formed in particular as tapered rollers. The rolling bodiesallow for relative rotation between the inner ring arrangement and theouter ring arrangement or between the two rotary partners, respectively.

For monitoring the working condition of the wheel bearing device, it hasan electric sensor device which detects the working condition usingmechanical contact. Preferably, the possible working conditions includea normal state of the intact wheel bearing device and/or an emergencystate when the wheel bearing device is damaged or subject tomalfunctioning. The sensor device presents a stationary sensor part,which is stationary in the vehicle, and a rotating sensor part, whichrotates together with the wheel, in which the two sensor parts can worktogether to form the mechanical contact.

Within the scope of the invention it is proposed that one of the sensorparts, namely without the interposition of the first rotary partner, isconnected to the inner ring arrangement in the mounted and/or unmountedstate of the wheel bearing device.

One consideration of the invention is to ascertain the possible damagingof the wheel bearing device as close as possible to the damage source tobe detected, that is placed in the contact zone outer ringarrangement—rolling body—inner ring arrangement. By the arrangement ofone of the sensor parts on or at the inner ring arrangement thesignificance of the detection by the sensor device is thus increased.Moreover, it is optionally possible to integrate the sensor part on orin the inner ring arrangement already in the production of the wheelbearing device, so that, if compared to the known state of the art, themounting expenditure is reduced during the final assembly of the wheelbearing device.

Altogether, the invention discloses a wheel bearing device for a motorvehicle with a sensor device, which can detect an imminent malfunctionof the wheel bearing, particularly of the ball bearing, with highvalidity. As will be explained in more detail in the following, thesensor device can react to an axial and/or radial shifting and/ortilting of the inner ring arrangement in relation to the outer ringarrangement. As an optional addition, the sensor device can also respondto an unusual temperature change in the region of the wheel bearingdevice.

In a preferred improvement of the invention, the other sensor part isconnected with the outer ring arrangement. This embodiment emphasizesonce more the idea of realizing a simplified mounting and at the sametime, higher detection security of the sensor device.

In an optional further development of the idea it is proposed that thewheel bearing device, with the two sensor parts already integrated, isformed as a pre-finished structural element. This further developmentcompletely excludes defective mounting during the installation of thesensor device after the installation of the wheel bearing device in thevehicle. Moreover, the sensor device can be set or calibrated in theproduction of the wheel bearing device.

In a possible constructive realization of the invention, one of thesensor elements presents a functional surface rotating around therotation axis of the wheel bearing device that is tracked by the othersensor part. In the case of an intact wheel bearing or in the normalstate, the other sensor element is distanced from the functional surfaceby a safety distance. In the case of signs of wear of the wheel bearingor in the emergency state and/or—as will be explained later—in the caseof a temperature increase in the area of the wheel bearing device, thesafety distance is reduced, and the other sensor element tracks thefunctional surface with mechanical contact. This reduction of the safetydistance can result particularly from a tilting or displacement of theinner ring arrangement in relation to the outer ring arrangement.

Preferably, the functional surface lies in a radial plane in relation tothe rotation axis, on a cylindrical surface concentric to the rotationaxis or on a conical surface. In other words, the functional surfaceextends with an angle of 90°, 0° or an intermediate angle of e.g. 45° inrelation to the rotation axis of the wheel bearing device.

In a particularly preferred embodiment of the invention, a surroundingelectric conductor arrangement is arranged on the functional surface.This conductor arrangement can be formed as an imprinting, a conductorpath and/or a conductor wire. The conductor arrangement is preferablyundulating, meandering, in a zigzag and/or in another arrangement in therotating direction, so that the conductor length of the conductorarrangement is greater than the circumference in the area of theconductor arrangement.

In a less preferred embodiment of the invention, the sensor deviceoperates according to a shutter principle, in which, in case ofmechanical contact of the sensor elements, a circuit is closed and asignal, as an indication of the wear or an irregularity of the wheelbearing device, is generated. In particular it can be provided that atthe mechanical contact, electrical contact between the sensor elementsis directly produced, or that first a protecting insulating layer musthe removed, before the two sensor elements short out.

In another more preferred embodiment, the sensor device operatesaccording to an opener principle, in which a signal is activated as soonas an or the electric conductor arrangement already described is openedin a or the sensor element. In the preferred embodiment, the conductorarrangement in one of the sensor elements is opened by abrasion by theother sensor element.

The conductor arrangement is formed in this preferred embodimentparticularly as a tripwire or a trip conductor.

In a preferred realization of the invention, the one sensor element withan electric conductor arrangement is formed as a sensor ring, which, ina preferred embodiment, is set on the inner ring arrangement.Optionally, the sensor ring is formed as a sealing ring, or integratedinto a sealing ring. For example the sealing ring can be formed as aprotective or tumbler ring in front of a cassette seal integrated in thewheel bearing device.

In an advantageous embodiment of the invention, the other sensor elementis formed as one or more sensor levers, which, in the preferredembodiment and optionally, while using intermediary elements, is mountedand/or fixed on the outer ring arrangement. In modified embodiments ofthe invention it is also possible that the sensor ring is placed on theouter ring arrangement and the sensor lever on the inner ringarrangement.

In a possible supplement to the invention, it is provided that at leastone sensor element is temperature-sensitive or reactive to temperature,so that in the case of a temperature increase over the normal operatingtemperature of the wheelbearing device, the safety distance between thesensor elements is reduced and/or that the two sensor elements makemechanical contact.

The sensor device can thus be shift-controlled andtemperature-controlled, and an activation of the sensor deviceelectively takes place by tilting the ring arrangements towards oneanother and/or by a temperature increase. Thus, the sensor devicemonitors both a mechanical displacement of the inner ring arrangementand the outer ring arrangement towards one another and the temperatureof the wheel bearing device. The realization of the temperaturesensitivity of the sensor element can be carried out by using a shapememory alloy (SMA). In this respect, a very high strength of the sensorlever(s) as well as the use of complex geometries is possible, since theshape memory alloy is malleable. Another possibility is the use of abimetallic arrangement, in which metals with different temperaturedependencies are connected to each other and, in the case of temperaturechange, react with a spatial offset. Another possibility is the use of agas, wax or metal (mercury/gallinstan) filled piston in a cylinder torealize an actuator principle, so that the expansion of the filler leadsto a shift of the sensor lever or of the sensor ring. In the case thatthe temperature sensitivity or dependence is insufficient to diminishthe safety distance appropriately, it is optionally proposed to augmenta temperature-sensitive shift by means of a lever gear or similardevice, so that the sensor lever and/or the sensor ring undergo(es) asufficient shifting. In this case, by way of the temperature reactingarrangement an actuator is triggered, which, as the sensor lever,contacts the other sensor element mechanically and activates the sensordevice.

In one preferred embodiment one of the sensor elements, particularly theother sensor element and in particular the sensor lever, is preferablyformed integrally and/or as an integral component of an ABS disc orencoder disc or a seal. These components are already present in thewheel bearing device, so that the integration of the sensor devicenecessitates only minor modifications of already existing wheel bearingdevices.

In case of a particularly preferred constructive realization, the outerring arrangement is rotating in the installation and the inner ringarrangement is stationary in the vehicle this embodiment, it ispreferred that the sensor ring is fixed on the inner ring arrangementand the sensor lever on the outer ring arrangement by means of the ABSdisc.

BRIEF DESCRIPTION OF THE INVENTION

Further features, benefits and effects of the invention result from thefollowing description of preferred embodiments of the invention. Thefigures show:

FIGS. 1-5 a first embodiment of the invention in variousrepresentations;

FIGS. 6, 7 a second embodiment of the invention in variousrepresentations;

FIGS. 8, 9 a third embodiment of the invention in variousrepresentations;

FIGS. 10-13 a fourth embodiment of the invention in variousrepresentations;

FIGS. 14-17 a fifth embodiment of the invention in variousrepresentations;

FIG. 18 a sixth embodiment of the invention in a schematic, cut 3Ddisplay.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 a, 1 b show, in a schematic, a longitudinal section and in aschematic three-dimensional representation, respectively, a wheelbearing device 1 as an embodiment of the invention, which is formed forthe rotatable mounting of an undepicted wheel on a vehicle, particularlya commercial vehicle.

The wheel bearing device 1 comprises an inner ring arrangement 2, whichcomprises inner rings adjacent to each other 3 a and 3 b in the axialdirection. The inner ring arrangement 2, and inner rings 3 a, 3 b,respectively, contain an axle stump 4 in a rotationally fixed way, whichis arranged stationarily in the vehicle or in the wheel suspension.

The wheel bearing device 1 further contains an outer ring arrangement 5,which is connected or connectable and rotationally fixed with the wheelnot depicted. In operation, the outer ring arrangement 5 rotatestogether with the wheel. The outer ring arrangement 5 comprises twoinserted outer rings 6 a, 6 b arranged separate towards one another.

Between the outer rings 6 a, 6 b and inner rings 3 a, 3 b rolling bodies7 are arranged in two rows, which are formed in this example as taperedrollers, however the rolling bodies can also have another form. Forsealing against dirt, the wheel bearing device 1 has a cassette seal 8on both sides.

In order to detect an imminent malfunction, an unusual working conditionor damage, the wheel bearing device 1 has a sensor device 9, which isformed as a switch, wherein by opening or closing two sensor elements ofthe sensor device 9, a circuit is opened or closed.

The mode of operation of the sensor device 9 is based on the fact that adefined distance—in the following also called a safety distance—betweena reference point on the outer ring arrangement and a reference point atthe inner ring arrangement 2, is observed. More precisely, it iscontrolled, if this safety distance decreases to or below zero.

Such a reduction of the safety distance can be caused, among otherthings, by a tilting or shifting of the inner ring arrangement 2relative to the outer ring arrangement 5 or by a deflection or wear ofthe wheel bearing device 1. Additionally or alternatively to this, thesensor device 9 can also be temperature sensitive, so that the switch isopened or closed when a determined operating temperature is exceeded.

FIG. 2 shows a schematic longitudinal section through the sensor device9, in which further components of the wheel bearing, device I are notrepresented. FIG. 3 shows the sensor device 9 in a detailed enlargement.As is shown from a synopsis of FIGS. 1 a, 2 and 3, the sensor device isformed by two sensor elements, i.e. a sensor ring 10 and a sensor lever12, arranged on a cover cap 11.

The sensor ring 10 has a radial fixing section directed inwards 13,which is clamped between the inner ring arrangement 2, particularly theouter inner ring 3 b and the axle stump 4, or is directly fixed on theinner ring arrangement. As the fixing section 13 is in direct contactwith the inner ring 3 b or the inner ring arrangement 2, its position isdefined with maximum precision. Radially outwards, the sensor ring 10has a U-shaped receptacle 14 opened in the axial direction, in whichfirst plastic layers 15 and—at the open side—a tripwire 16 are arranged.As is shown best in FIG. 4, the tripwire 16 is formed as a continuouswire, however partially covered in the representation, which extends ina regular pattern in the rotational direction around the rotation axisof the wheel bearing device 1. It is, furthermore, particularlyadvantageous for the sensor ring 10 to take up a double function, it isalso formed as a sealing ring 19 for the protection of the cassette seal8 in addition to the sensor function. The sensor lever 12 is formed as afree projection on the cover cap 11, pointing axially inwards, while—asalso shown in FIG. 4—several sensor levers 12 are distributedequidistant in the rotational direction.

Both the sensor ring 10 and the cover cap 11 and thus the sensor lever12, by resting directly against the outer ring arrangement 5 or theinner ring arrangement 2, are defined very accurately in their position,so that in the case of an intact state of the wheel bearing device 1, asafety distance (s) is formed between the tripwire 16 and the free endof the sensor lever 12.

In the case that the outer ring arrangement 5 and inner ring arrangement2 tilt towards one another or shift towards one another, the safetydistance (s) reduces until mechanical contact between the sensor levers12 and the tripwire 16 arises. If the safety distance (s) diminishesfurther, the sensor lever 12 erodes the tripwire 16 at leastsectionally, so that its conductivity is interrupted.

The conductivity of the tripwire 16 is permanently monitored, so that onthe one hand, the correct operability of the sensor device 9 iscontrollable and on the other hand, a cutting of the tripwire 16 by thesensor lever 12 is immediately detectable. As soon as such damage isdetected, an alert signal is issued to the driver meaning that the wheelbearing device 1 is defective or no longer in sufficient workingcondition.

In a further embodiment of the invention not shown, it can additionallybe provided that the sensor lever 12 is formed and/or arranged astemperature-sensitive, so that with increasing temperature safetydistance (s) is reduced, The design of the sensor lever 12 is selectedso that, if a temperature limit is reached, the safety distance (s) isreduced and, in an analogous way, as in the case of tilting or shifting,the tripwire 16 is eroded and its conductivity is interrupted. Thus, inthis improvement, the sensor device 9 is both sensitive to shifts and totemperature increases of the wheel bearing device 1.

As an alternative to this embodiment, the tripwire 16 can also, in itscourse, have at least one temperature-sensitive section, which reacts assoon as a temperature limit is exceeded. The reaction of thetemperature-sensitive section is fulfilled preferably by a temperaturesensitive sensor element. In this way, the tripwire 16 occupies anotherfunction, namely as a signal line for the temperature sensitive sensorelement.

In modified embodiments of the invention it is also possible that thesensor lever 12 does not, as illustrated in FIG. 1 a, engage from thefree axial side in the sensor ring 10, but is arranged protected and isin the internal space of the wheel bearing device 1 and abuts from theinner side against an inversely formed sensor ring 10 (compare also FIG.18).

FIG. 5 shows a schematic three-dimensional representation of the sectionin FIG. 3, in which it can be seen how the sensor lever 12, which isarranged integrally on the cover cap 11, engages in the seat 14 of thesensor ring 10 in order to detach the tripwire 16.

FIGS. 6 and 7 show another embodiment of the invention, in which equalreference signs indicate the same parts as in the preceding Figures. Ina differentiation from the embodiment in the FIGS. 1 to 5, even thoughthe sensor ring 10 is embodied similar or identical in the secondembodiment of FIGS. 6 and 7, the sensor levers 12 are not, however, anintegral component of a cover cap 11, but are formed integrally on anABS disc or encoder disc 17, In this embodiment, correspondingly, themounting for the sensor lever 12 also has another function, i.e. asencoder disc 17.

As shown particularly in FIG. 6, the ABS disc 17 rests directly on acarrying body of the outer ring arrangement 5, so that—as in thepreceding figures—a high positioning accuracy of the sensor lever 12 isreached.

FIGS. 8 and 9 show a modified embodiment of the second embodiment in theFIGS. 6 and 7, in which, unlike the preceding embodiment, the sensorring 10 comprises a printed conductor path 18 instead of the tripwire16, but which is built and functions in an analogous way as the tripwire16.

The preceding embodiments showed the detection of tilting/shiftingand/or a temperature change of the wheel bearing device 1 by adisplacement of the sensor lever 12 in relation to the sensor disc 10 inan axial direction. FIGS. 10 to 13, on the other hand, illustrate asensor device 9 with a sensor lever 12, which affects the tripwire 16 inthe radial direction as another embodiment of the invention.

FIG. 10 shows a longitudinal section through the sensor disc 10 as wellas a cover cap 11, which differentiate from the embodiment in the FIGS.2 and 3 substantially by the fact that the seat 14 of the sensor disc 10is radially open towards the outside and the tripwire 16 constitutes afunctional surface, which is arranged in a cylinder surface form andconcentrically to the rotation axis of the wheel bearing device 1.

In FIG. 11, which shows a detailed enlargement of FIG. 10 it can be seenthat the safety distance (s) is arranged in a radial direction thistime. FIGS. 12 and 13 show the sensor device 9 in a three-dimensionalrepresentation and in a detailed representation of the detail 1 in FIG.12, in which it can be seen that four sensor levers 12 engage in aradial direction into the seat 14 of the sensor disc 10.

The FIGS. 14 to 17 show a further embodiment of the invention, in whichthe sensor ring 10 with the tripwire 16, in differentiation from thepreceding embodiments, constitute a functional surface, which isconically designed and occupies an angle of approximately 45° inrelation to the rotation axis of the wheel bearing device 1. The sensorlever 12 is formed as a separate component, which is integrated into acover cap 11, this embodiment offering the option for the sensor lever12 to be formed of temperature sensitive material, so that in the caseof a temperature increase, the safety distance s between the free end ofthe sensor lever 12 and the functional surface of the sensor ring 10 orthe tripwire 16 is reduced. FIG. 17 shows the fourth embodiment in athree-dimensional representation.

The next embodiment in FIG. 18 is formed in a similar way as the firstembodiment, in which the sensor ring 10, on its radial inner area,comprises a collar shaped molding, which encompasses the inner ring 3 bpositively, so that a form-fit fixing of the sensor ring 10 on the innerring 3 b is ensured. Generally, it is preferred that the sensor ring 10or the sensor element is undetachably fixed on the inner ringarrangement 2. Thus, this fixing of the sensor ring 10 can also be usedin the other embodiments. The sensor lever 12 engages—as mentionedbefore—not from axially outside, but laterally from the inside of thewheel bearing device 1 into a seat 14 of the sensor disc.

The invention claimed is:
 1. A wheel bearing device for a motor vehicle,comprising: an inner ring arrangement, which is formed for rotationallyfixed reception of a first rotary partner; an outer ring arrangement,which is connectable with a second rotary partner in a rotationallyfixed manner; a multitude of rolling elements, which roil between theinner ring arrangement and the outer ring arrangement so that the innerring arrangement and the outer ring arrangement and/or the first rotarypartner and the second rotary partner are rotatable against each other;an electric sensor device, which, using a mechanical contact fordetecting a working condition of the wheel bearing device, comprises astationary sensor element and a rotating sensor element which togetherform the mechanical contact, wherein the stationary sensor element isconnected with the inner ring arrangement without interposition of thefirst rotary partner; and the stationary sensor element including anelectric conductor arrangement, wherein the sensor device operatesaccording to an opener principle, in which a signal is activated as soonas the electric conductor arrangement is opened in the stationary sensorelement, wherein the stationary element comprises a functional surfacesurrounding a rotation axis of the wheel bearing device, the rotatingsensor element faces the functional surface and rotates along, acircular path, and the electric conductor arrangement is arranged on thefunctional surface and extends circumferentially in an undulatingpattern along the functional surface.
 2. The wheel bearing deviceaccording to claim 1, wherein the functional surface is tracked inoperation by the rotating sensor element distanced with a safetydistance or with the mechanical contact.
 3. The wheel bearing deviceaccording to claim 2, wherein the functional surface is arranged on oneof a radial plane in relation to the rotation axis of the wheel bearingdevice and a conical surface arranged concentrically in relation to therotation axis of the wheel bearing device.
 4. The wheel bearing deviceaccording to claim 1, wherein the rotating sensor element includes acover cap connected to the outer ring arrangement and a sensor levercomprising a projection having a free end facing the functional surface.